An 8-year-old Friesian gelding was referred to the Cornell University Large Animal Hospital Emergency Service after being found down and thrashing in his stall, and non responsive to medical management attempted by the referring veterinarian. On presentation, the patient was very anxious, mildly dehydrated, borborygmi were diminished in all abdominal quadrants, and multiple loops of distended small intestine were palpated on rectal examination. Abdominal ultrasound revealed markedly distended loops of small intestine (largest section 8.2cm found in the right abdominal quadrants) with normal intestinal wall thickness. An exploratory celiotomy was performed and a right, dorsal diaphragmatic hernia was palpated with approximately three feet of incarcerated jejunum and ileum being displaced into the thoracic cavity; a thoracic rib fracture was also identified. The incarcerated small intestine was resected and an end-to-end jejunoileosomy was performed. Prior to recovery from general anesthesia, a thoracostomy tube was placed. During the post-operative recovery period, the patient experienced multiple complications, including diffuse small intestinal ileus, enterocolitis, severe diarrhea, and a ventral abdominal incisional infection. This case report describes some aspects of the diagnostic, medical, and surgical management of this patient.